Abstract: A high frequency voltage generator (10) produces a high positive voltage and a high negative voltage. A parallel connected coil (26) and diode (30) are connected between the high voltage supply and a target (44) of an x-ray tube (40). A second parallel connected coil (28) and diode (32) are connected between the negative voltage and an electron source (42) of the x-ray tube. The coils are preferably a multiple pancake design (FIG. 3 ). When the tube starts to arc, the sudden increase in current flow through the coil is converted and stored in a magnetic field leaving only a small current to contribute to arcing. The coils are sized such that the current which passes to the x-ray tube is sufficiently small that the arcing is usually extinguished without an avalanche phenomenon occurring.

Abstract: A rotor speed adjustment circuit (60) reduces the rotational speed of an anode (32) of an x-ray tube (14) in a diagnostic apparatus (10). An AC current (64) from an AC current source (54) is applied to one stator winding (52). A parallel connected diode (70) and resistor (72) are connected between the current source and a second stator winding (50) to cause an effective DC magnetic braking component (66b) which reduces the rotational speed of the anode and an associated rotor (42). By selectively adjusting the resistor (72), the size of the DC magnetic braking component, hence the amount of effective drag is selectively adjustable to adjust the anode rotation speed.

Abstract: A coolant oil from an x-ray tube (14) is circulated through a heat exchanger (18) to reduce its temperature. More specifically, at least one hot coolant fluid receiving aperture (30) is defined adajcent an end of a suction tube 32) in an upper most portion of a horn portion (16) surrounding a cathode termination assembly. Bubblers (42) of gas in the fluid which could be ionized by electrical fields inside the x-ray tube housing causing x-ray tube current irregularities and corresponding x-ray tube output irregularities are drawn into the suction tube aperture. A debubbler (38) removes bubbles from the cooled coolant fluid before it is returned into an anode horn portion (20) of the x-ray tube. Alternately, the bubbles may be reabsorbed, dissolved, or homogenized by the action of the heat exchanger and pump. The coolant fluid passes through a central portion (24) of the x-ray tube absorbing heat and back to the cathode horn portion.

Abstract: An x-ray tube is disclosed whose cathode cup is battery biased at a low level, approximately 30 volts DC, to inhibit "wings" on the focal spot of electrons bombarding the anode. The battery for providing bias, floats at the DC electrical potential applied to the cathode, many KV below ground potential. Geometric modifications to the filament/focusing cup arrangement are also included. The geometrical characteristics partially inhibit the dispersion of electrons, inhibiting the formation of "wings" on the x-ray focal spot, particularly at high current levels. At lower current levels, the low DC battery bias enhances the anti-dispersion effects of the geometrical characteristics to inhibit wing formation even at these lower current levels.

Abstract: An X-ray tube having two individually energizable cathode filaments. If a primary filament is shorted to a cathode cup, a switch mounted inside the tube housing is thrown to couple a second filament to a filament energization signal. This avoids the necessity in replacing the X-ray tube if the primary filament is shorted and lengthens the effective life of the X-ray tube.

Abstract: An X-ray tube having a capability to produce multiple anode spots. The X-ray tube can produce three or more different size anode focal spots without modification of the connectors, cabling, or high voltage supply for routing high voltage signals to the X-ray tube. An isolating fiber optic control input connects an external light emitting diode to a controller inside the tube housing. The controller responds to light signals from the light emitting diode to control the size of focus spots on the tube anode. In a preferred embodiment each of three filaments are individually energized to produce three different size focal spots and a cathode cup to which the filaments are mounted is also biased to add a four spot capability. In an alternate embodiment a split or segmented cathode cup has its segments biased to different electrical potentials by tapping power from a conventional high voltage filament supply used in energizing a cathode filament.

Abstract: The inner surface of an X-ray tube envelope is constructed to prevent the build-up of an electrically conductive layer of metal deposits on the tube envelope in the regions adjacent to and between the cathode focusing element and the anode. In the disclosed embodiment this area is textured so that metal deposits can only collect in certain places and not in others. The places of metal collection are spaced so that the development of a conductive metal layer is inhibited. By properly texturing the inner surface of the envelope, this spaced collection of metal is so effective that the spaced regions of metal build-up are electrically insulated from one another. A method is disclosed comprising first mechanically abrading the inner surface of the envelope to create small fracture regions. Thereafter, the abraded surface is acid-etched. The acid attacks the areas of the envelope which exhibits these fracture regions creating relatively deep and narrow "canyons" surrounding "islands".

Abstract: An X-ray tube includes a rotor body having an outer sleeve of copper and an inner sleeve of steel, the two sleeves being joined by brazing. A black coating is applied to the outer surface of the copper sleeve and the inner surface of the steel sleeve, as well as to the outer surface of a copper bearing housing concentrically disposed within the rotor body. A steel spindle is concentrically and rotatably supported within the housing by a bearing structure and is rigidly affixed to the rotor body to support the rotor body for rotation. The X-ray tube also includes an anode comprised of molybdenum having a coating of rhenium-tungsten. The anode is supported on a shaft comprised of a material having a low coefficient of thermal conductivity such as niobium, an alloy of niobium, molybdenum, or an alloy of molybdenum. The X-ray tube further includes a bearing structure having portions lubricated by lead.